Declaring Vaccine Hesitancy One of the Ten Biggest Health Threats in 2019 Is Unhelpful

None of the currently used vaccines were tested in randomized trials to document that they were overall beneficial before being introduced. And once a vaccine is recommended, it is almost impossible to study it in randomized trials because most ethical committees would not allow researchers to deprive a child of a recommended vaccine.

There is now increasing evidence that vaccines may have non-specific effects. They alter the immune system more broadly and so may affect the risk of other infections. Sometimes, for live vaccines such as the measles vaccine and oral polio vaccine, this seems to enhance the capability of fighting off other infections. Unfortunately, inactivated vaccines, such as the DTP vaccine, seem to increase the risk of other infections, particularly for females.

We do not have the evidence for all vaccines to tell vaccine-hesitant parents that it is overall beneficial for their child to receive each one of them. Rather, we have to acknowledge that there are things about vaccines that have not been investigated very well.

Most vaccine-hesitant parents that I have come across are concerned that vaccines have not been investigated for their overall health effects. Telling them that the science is settled and stigmatizing them for their hesitance and mandating vaccines is inadequate and will only increase the popular opposition and hesitancy.

New Conversation
A good starting point for the new conversation we need to have with vaccine-hesitant parents is to stop talking about vaccines in plural, but discuss them individually. They are, after all, as different as drugs. And just as it would not make sense to say that “drugs work” it makes little sense to state that “vaccines work”.

There is considerable evidence that live vaccines, such as the measles vaccine, have beneficial effects on overall health – reducing the risk of measles and other infections, thereby the risk of dying. But we must admit that we do not have the same kind of evidence for other vaccines.

As health professionals, we can give people advice along the lines of “If it was my child, I would…” – but given the lack of evidence, we should not judge parents who choose not to vaccinate. And we should not mandate vaccines.

It would be wonderful to eradicate measles, but that can be achieved with a vaccination coverage of 95 percent – the point at which herd immunity is achieved. And it is still only a small percentage of the population that does not want to vaccinate – so if we vaccinate those who want to vaccinate, then eradication is within reach, without shaming or forcing vaccine-hesitant parents. If we manage to eradicate measles, we may want to continue the vaccination for its beneficial non-specific effects.

Regarding other vaccines, where evidence for overall benefit is missing, we need randomized trials of their effect on overall health to provide the safety evidence that parents rightly request. Rather than making vaccine hesitancy a top-ten threat, the WHO should make it a top-ten priority to follow-up on its decision from 2014 to further investigate the overall health effects of vaccines.

Christine Stabell Benn is Professor of Global Health, University of Southern Denmark. This article is published courtesy of The Conversation.